As Bay Bridge deals with controversy, Golden Gate seismic works plods along

AS CALTRANS struggles to get the Bay Bridge's seismic fix finalized, officials report no such problems on the Golden Gate Bridge, though completion of its seismic work is still at least six years off.

In the past two months the $6.4 billion Bay Bridge seismic project — which includes a new span — has been thrown into controversy after it was divulged that steel anchor rods became brittle and snapped. Now it is unclear if the new span will open by Labor Day as planned.

Bolts made from the same material were used on the Richmond-San Rafael Bridge retrofit completed in 2006, but have been deemed safe.

On the Golden Gate Bridge — used by more than 100,000 people each day — a $660 million seismic retrofit project designed to allow the bridge to withstand an 8.3-magnitude earthquake has not run into any such problems as it plods along.

"Everyone has a defined role on the project," said Ewa Bauer, chief engineer of the bridge. "We also have procedures for every material that we build into our project. It's a full chain of paperwork and documentation."

Not only are materials inspected by the manufacturer, but by bridge staff as well.

"There is a lot of redundancy," said Mary Currie, bridge district spokeswoman.

This fall, work will be finished on the next to last segment of seismic work. "Phase 3A" has seen the strengthening of the north anchorage house — the box-like structure the length of a football field, which holds all the cables coming off the span that tie down the structure.

"The heavy work inside the anchorage house has been completed," Bauer said. "We have some small things to finish; it will all be done by the fall."

Work on the first phase of the seismic project, strengthening the north approach, was finished in spring 2002. Work on the second phase, along the south approach, was finished in 2007.

Work for the final "Phase 3B" — addressing the center suspension portion of the span — will cost $220 million and bridge officials are seeking funding for that work in Washington, D.C.

The work will include strengthening the bases of the towers, truss work, expansion joint modification and designs to better dissipate the energy of an earthquake.

"The bridge is much stronger than it was 10 years ago, but we still have the work to do on the suspension portion so it will remain standing after a big earthquake."

While the suspension portion is sturdy, it could sustain damage if a 7.0-magnitude or larger quake hits in close proximity to the span, officials said.

"It's a race against time," said Currie, adding that the Golden Gate has the advantage of its towers being built into bedrock.

Bauer noted the retrofit phases have been staged by importance. The approaches were the most vulnerable to shaking, the suspension portion the least.

"The suspension portion of the bridge is designed to move," she said. The center span of the bridge is designed to swing as much as 27 feet in each direction.

Why will it take more than two decades to finish the work?

"The money has come in small chunks," Bauer said, noting the project is still not fully funded. "Also, after 9/11, there had to be some redesigns."

The terror attack, which occurred in the early stages of the seismic retrofit project, forced bridge officials to rethink their plan beyond earthquakes.

Officials examined ways to "harden" the towers "to protect against blast" in 2005. Additional computer modeling to determine how strengthened towers would react during an earthquake were among the issues studied.

When the strengthening work is finished, Bauer believes the 76-year-old span will be ready to serve the public for generations to come.

"It can stand forever, we just need to fix and maintain it, like you do with your home," she said. "There are many great buildings around the world that are hundreds and hundreds of years old."

Meanwhile, Marin's other major bridge — the Richmond-San Rafael — has had its seismic work completed. The bridge — which carries 60,000 cars a day — underwent a five-year, $778 million seismic upgrade that was overseen by Caltrans. It included replacement of the trestle section of the span on the Marin side, where holes opened in the roadway.

Caltrans did find 772 high-strength bolts on the bridge that are made of the same type and grade of steel as those that broke on the new Bay Bridge span. Installed in 2005, however, these bolts are "snug tight" and not under a tension level that would make them brittle, engineers have said.

Contact Mark Prado via email at mprado@marinij.com; Bay Area News Group contributed to this report.